Dextrin

Dextrin is a starch product that is dissolved in water to form a
liquid binder. As this product is sensitive to decay it is
necessary to add a preservative. Dextrin is the binder of Talens
Gouache extra fine and of the other quality poster paints. A
special property of a dextrin solution is thixotropy. If we leave
the paint alone it will automatically thicken. Through movement
(stirring or painting) the paint becomes thinner again and will
easily spread out.